Printing telegraph transmitter control



Sept. 8, 1959 F P. MASON ETAL PRINTING TELEGRAPH TRANSMITTER CONTROL Filed Jan. 23, 1956 Motor Clutch Inventors E P MASON R- G.STEMP ttorney U ted States l atent O PRllI-T'ING TELEGRAPH TRANSMITTER CONTROL Frederick Percival Mason and Ronald Gilbert Stomp, Croydon, England, assignors to Creed & Company Limited, Croydon, England, a British company Application-January 23, 1956, Serial No. 560,837

Claims. priority, application Great Britain January 26, 1955- 11 Claims. (Cl. 192-.02)=

been switched off from the motor and the speed of the motor therefore begins to fall any signal elements thereafter Will be mutilated.

v It is the object of the present invention to provide a simple means for preventing operation of the transmitting mechanism except when the motor has reached transmission speed.

It has been previously proposed to provide a tape con trolled transmitter driven from a motor through a. friction clutch and to provide a mechanical device which renders the clutch effective after the motor has completed a given number of turns. Apart from the fact that the mechanism is complicated and expensive to manufacture, a time lag instituted in this manner is not absolutely positive as it is dependent on a fixed number of revolutions of'the motor shaft only which is no criterion as to whether full speed has been reached.

In another proposal the transmitter contacts are maintained short circuited until a stop arm is releasedby the motor reaching its correct speed. This stop arm restores the short circuit across the transmitter contacts once per cycle during the stop period and when the stop button to disconnectt-he motor isv operated :the stop arm is held in the position in which it maintains .the short circuit across the transmitter contacts, thus preventing trans,

mission of signals during the slowing down of the motor.

The present invention relates to telegraph transmitters driven by motors whose speed is controlled by centrifugally operated contacts.

According to the present invention there is provided means for controlling the starting of a telegraph transmitter driven by a motor of which the speed is governed by centrifugally operated contacts comprising a clutch through which the power developed by the motor is transmitted to the transmitter the engagement of said clutch being under the control of said contacts.

An embodiment of the invention will now be described with reference to the accompanying drawing in which Fig. l is a block diagram of the equipment used in applying the invention, and Fig. 2 is a diagram of a preferred embodiment of the control circuit of the invention.

This drawing shows the circuits for controlling the supply of power to the clutch electromagnet. Two manually operated switches may be provided, one of which is a manual motor switch MMS, and the other a manual line switch MLS. The manual motor switch MMS has two separate contacts 1 and In, both normally in open condition. When the switch is operated contacts 1 connect the power supply P to the motor M. When the motor reaches the desired speed the centrifugally operated motor governing contacts 2 open and the inductive motor energy is dissipated by the how of oscillatory current via capacitor C. The oscillatory potential developed across capacitor C is applied via contacts 1a of the switch MMS to a full wave rectifying bridge 4, 5, '6 and 7 and the Winding 8 of a relay R.

The relay R .closes four contacts r1, r2, r3 and r4; r1 forms a bridge across contacts -1 of the switch MMS. Contact r3 connects a governing resistor 3 across the contacts 2 and diverts part of the current flowing through the rectifier bridge and winding 8 of the relay R. The resistor 3 is of sufliciently great a resistance to ensure that this winding of the relay draws sufiicient current to remain operated. The purpose of resistor 3 is to assist in dissipating inductive energy from :the motor during subsequent operations :of contacts '2.

The closing of contacts r2 prepares the clutch magnet ZCRM for operation. The completion of the circuit of this magnet depends .upon contacts 12. of the manual line switch MLS. When transmission is required to commence the switch MLS is operated thus causing energisa tion of the clutch magnet CRM which causes the clutch between the motor M and the transmitter (not shown) to be efiective and transmission of signals commences. The right-hand winding 9 of the relay R receives current from the circuit operating the clutch magnet through the rectifier it? and this keeps the relay R operated. It will be noted that it is impossible for transmission to commence at any speed other than the correct speed, even if the two switches MMS and MLS are operated simultaneously, since the magent CRM is not operated until contacts 112 are closed and these contacts are only closed when the motor has attained governed speed.

A second pair of contacts, such as contacts 12a, may be provided on the switch MLS which serves to short circuit, when the'contacts r4 are closed, the wires a and b which are connected to the transmitting contact circuit of "an associated auxiliary transmitter transmitting over .the same channel as the main transmitter andthus prevent any interference with the main transmitter by the auxiliary transmitter.

In this connection both transmitters are assumed to be of the single-current type, which, when sharing the same channel, are connected in series. Single-current transmitters are always so arranged that when the transmitter is inert its signalling contacts are closed. Thus when the contacts of one are generating signals the contacts of the other carry these signals to the communication line and must not be inadvertently operated. An arrangement of this kind is shown in the drawing wherein x are the contacts of the automatic transmitter and y are the contacts of an associated keyboard transmitter; x and y are connected in series with a source z for signalling to the line comprising conductors 1 and 1 It Will be seen that contacts 1'2a and r4, when closed, shortcircuit by the agency of conductors a and b the contacts y of the auxiliary keyboard transmitter thus precluding disturbance to the signals generated by contacts x by inadvertent opening of contacts y.

Any inadvertent short circuiting of the contacts of the auxiliary transmitter by operation of the manual switch MLS without the closure of the motor switch is prevented by the presence of the contacts r4 in the short ctrcuiting wires.

When transmission from the main transmitter is required to cease the two switches MMS and. MLS are opened. The holding winding 9 of the relay R is thus opened but a rectifier 11 connected across this winding renders the relay R slow to release and introduces therefore a time lag in the falling off of the relay armature. This time lag enables the cam sleeve of the transmitter to complete its revolution at governed speed. When the relay finally releases the contacts r1, r2, r3 and r4 open and bring the machine into its rest condition. The presence of rectifier prevents the rectifier 11 from making the magnet CRM slow to release.

If the transmitter is tape controlled, contacts 13, which openwhen the tape through the transmitter becomes taut, may be provided in the circuit of the clutch release magnet to stop the transmitter and prevent the tape from being torn.

While the principles of the invention have been described above in connection with specific embodiments, and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What we claim is:

1. Means for controlling the starting of a motor driven device until its drive motor attains a predetermined rate of rotation comprising a source of motor potential, clutch means for clutching said device to said drive motor, a pair of centrifugally operated contacts under control of said motor, said contacts serially disposed between said source and said motor, means for deriving a control potential from the inductive energy of said motor upon the operation of said contacts and an electromagnetic relay responsive to said control potential for controlling the operation of said clutch means.

2. Means for controlling the starting of a motor driven device as claimed in claim 1 wherein said means for deriving a control potential comprises a capacitor in shunt with said contacts, and rectifier means coupled between said relay and said capacitor for rectifying oscillatory current flowing in said capacitor incident to the operation of said contacts.

3. Means for controlling the starting of a motor driven device as claimed in claim 2, wherein said electromagnetic relay comprises contacts in series connection between said clutch means and its operating potential.

4. Means for controlling the starting of a motor driven device as claimed in claim 1, wherein said contacts comprise a pair of normally closed contacts adapted to open when said motor attains a predetermined rate of rotation.

5. Means for controlling the starting of a motor driven device as claimed in claim 3, further comprising a pair of manually operated contacts in series connection with clutch means, said relay contacts and said operating po tential, whereby said clutch is inoperable unless both said relay contacts and said manually operated contacts have been operated.

6. Means for controlling the starting of a motor driven device as claimed in claim 5, wherein said manually operated contacts further comprise a pair of contacts for disabling operation of a further motor driven device coupled with said first-mentioned device.

7. Means for controlling the starting of a motor driven device until its drive motor attains a predetermined speed comprising a source of current, a clutch magnet for clutching said device to said drive motor, a pair of centrifugally operated contacts under control of said motor, said contacts being connected in the circuit of said drive motor and source of current, a capacitor connected in shunt with said contacts, an electromagnetic relay, rectifier means coupled between said capacitor and a winding of said relay, and an energizing circuit for said clutch magnet including contacts of said relay.

8. Means for controlling the starting of a motor driven device as claimed in claim 7, further comprising manually operable switch means in the energizing circuit of said clutch magnet, and a holding winding on said relay, said holding winding being connected in parallel relation to said clutch magnet.

9. Means for controlling the starting of a motor driven device as claimed in claim 8, further comprising a rectifier connected across said holding winding to render said relay slow to release.

10. Means for controlling the starting of a motor driven device as claimed in claim 9, comprising a further rectifier connected between one end of said holding winding and one side of said clutch magnet.

11. Means for controlling the starting of a motor driven device until its motor attains a predetermined speed comprising a source of current, a clutch magnet for clutching said device to said motor, a pair of centrifugally operated contacts under control of said motor, first and second manually operable switch contacts, an energizing circuit for said motor including said centrifugally operated contacts and said first manually operable switch contacts, a clutch magnet for clutching said device to said motor, a capacitor connected in shunt with said centrifugally operated contacts, an electromagnetic relay having an operating winding and a holding winding, rectifier means coupled between said capacitor and said operating winding, means connecting said holding winding in parallel with said clutch magnet, an energizing circuit for said clutch magnet including a first pair of contacts controlled by said relay and said second manually operable switch contacts, and a second pair of contacts controlled by said relay and connected in shunt with said first manually operable switch contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,264,378 Dixon Apr. 30, 1918 1,632,297 Kleinschmidt June 14, 1927 1,948,037 Kingston Feb. 20, 1934 1,985,640 Kitchens Dec. 25, 1934 2,054,479 Hoddy Sept. 15, 1936 2,608,615 Oberman Aug. 26, 1952 

